1. Field of the Invention
The present invention relates to a method of producing a polymeric fluorescent substance and a polymer light-emitting device (hereinafter, sometimes referred to as polymer LED) using the same.
2. Description of the Related Art
Light-emitting materials having high molecular weight (polymeric fluorescent substances) are, differing from those having low molecular weight, soluble in a solvent and can form a light-emitting layer in a light emitting device by a coating method, consequently, have been variously investigated, and for example, there are disclosed polyarylene-based polymeric fluorescent substances such as polyfluorene (Jpn. J. Appl. Phys., vol. 30, L 1941 (1991)), poly-p-phenylene derivatives (Adv. Mater., vol. 4, p. 36 (1992)) and the like.
As a method of producing a polyarylene-based polymeric fluorescent substance, a method is known in which a dihalogenated arylene of the formula:X—Ar—X(X represents a halogen atom and Ar represents an arylene group) is polymerized in the presence of a zerovalent nickel complex. For example, there is a disclosure in which 9,9-dioctyl-2,7-dibromofluorene is polymerizedin the presence of Ni(COD)2 in a tetrahydrofuran solvent to obtain polydioctylfluorene (weight-average molecular weight: 54000)(Tokito et al., Monthly Display, pages 26-32 (2000), TechnoTimes Co., Ltd.).
However, the molecular weight of a polyarylene-based fluorescent polymer produced by the above-mentioned conventional method is not sufficiently high yet, and there has been demanded for a method which can produce those having further higher molecular weight.
An object of the present invention is to provide a method in which an arylene-based monomer having two leaving groups such as dihalogenated arylenes and the like is polymerized in the presence of a zerovalent nickel complex to produce a polyarylene-based fluorescent polymer having high molecular weight; a polymeric fluorescent substance produced by the method; and a polymer LED which can be driven at low voltage and at high efficiency using the polymeric fluorescent substance.